Apparatus for reducing stress in a mounting plate

Abstract

Apparatus for mounting one or more component parts of a unit in assembly. The apparatus includes a mounting plate containing one or more extruded holes each having a raised lip surrounding the hole which protrudes upwardly from the top surface of the plate for receiving a threaded fastener that is used to secure a part to the bottom mounting surface of the plate. An endless depression surrounds each hole which also protrudes outwardly from the top surface of the plate. The size and shape of the depression is such that the plate area surrounding the fastener receiving hole is strong enough to resist high impact loads.

We claim:  
     
         1 . Apparatus for mounting parts to an assembly that includes: 
 a mounting plate having a flat top surface and a bottom surface;    at least one hole passing through said plate for receiving a threaded fastener;    an endless depression formed in said plate that surrounds said hole, said depression protruding upwardly from the top surface of the plate; and    said depression having a size and a shape such that the magnitude of stresses resulting from impact loads about the said at least one hole are reduced to a level below the yield strength of the plate.    
     
     
         2 . The apparatus of  claim 1  wherein said depression is circular and is centered upon the center of said hole.  
     
     
         3 . The apparatus of  claim 2  wherein said depression is arcuate in cross section.  
     
     
         4 . The apparatus of  claim 1  wherein said plate is fabricated of sheet metal and the threaded fastener is a self tapping or thread forming screw.  
     
     
         5 . The apparatus of  claim 1  that further includes a plurality of holes, each hole being surrounded by an endless depression.  
     
     
         6 . The apparatus of  claim 1  that further includes a flat section of plates separating the depression and the at least one hole.